Question: Simplify the following expression: $n = \dfrac{1}{4z} - \dfrac{1}{2z}$
Solution: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $4z$ and $2z$ $\lcm(4z, 2z) = 4z$ $ n = \dfrac{1}{1} \cdot \dfrac{1}{4z} - \dfrac{2}{2} \cdot \dfrac{1}{2z} $ $n = \dfrac{1}{4z} - \dfrac{2}{4z}$ $n = \dfrac{1 -2}{4z}$ $n = \dfrac{-1}{4z}$